How can something virtually obtained count towards real items? We're talking about items in THE store, right? Cuz that would be terrible. If we are now talking about virtual counting towards virtual, then that's fine, if you perform it correctly.
Why must there be a different value to go towards something different? You can have AP to count for two things. In fact, it's programmable. It's like a mathematical function, where one integer can pair up with multiple integers. If you have AP to count towards the points you gain and the points you spend, there is no fuss on multiple circumstances. Everything will be simple if you have AP represent two different values or variables.